Richard Strauss - Last Four Songs

Last year I posted the same question and received many nice suggestions. The recording mentioned most was performed by Schwarzkopf with Szell (EMI 24356-69602).

Now I collected more recordings of this compositions,

1. Flagstad with Furtwangler,
Philharmonia Orchestra (world premiere in 1950)
2. Schwarzkopf with Ackermann,
Philharmonia Orchestra (1953)
3. Schwarzkopf with Szell,
Concertgebouw Orchestra (1964)
4. Schwarzkopf with Szell,
Berlin Radio Symphony Orchestra (1966)
5. Janowitz with Karajan,
Berlin Philharmonic Orchestra (1974)
6. Norman with Masur,
Leopzig Gewanhaus Orchestra (1983)
7. Popp with Tennstedt,
London Philharmonic Orchestra (1982)
8. Studer with Sinopoli,
Staatkapelle Dresden (1994)
9. Bonney with Martineau (piano, 1999)

and I find all three performances by Schwarzkopf are somehow lack of the darkiness these songs try to delivery.

I am still struggling to find other nice performances. Please advise your suggestion(s).

Thanks in advance adn happy listening.

Otto